DESCRIPTION (From the application): The proposed research explores the interval timing abilities of healthy older adults. Given the central role time plays in basic learning and memory, results of research into the cognitive and neural basis of timing dysfunction related to aging may lay the groundwork for better understanding of a wider range of age-related cognitive deficits. The proposed research has three objectives: (1) to determine whether timing is more easily disrupted by non-timing processing in older participants than in younger ones. This issue is addressed in two experiments that assess older subjects' performance with a dual-task method used previously to study college-aged students. This task combines aspects of choice reaction time and time production tasks, and allows for careful control of the difficulty of the non-timing task. Interference may result in changes to both timing accuracy and variability. (2) To compare and contrast performance of Parkinson's disease (PD) patients with that of healthy older adults on the tasks used in (1). Similarities among behavioral timing deficits in akinetic PD patients and older controls may indicate that dopamine depletion underlies deficits in both groups. (3) To determine whether aging impairs the processing of time in non-timing tasks. In warning signal paradigms, a signal indicates to the subject the impending arrival of an imperative stimulus. The duration of the warning signal partially determines the reaction time in young subjects. If age leads to impairment of a timing system that underlies temporal processing of the warning signal, then the reaction time of older subjects may be less affected by warning signal duration than the reaction time of younger subjects. The proposed training program will concentrate on skills necessary to conduct research on aged and neurologically impaired populations. This includes coursework, training in the administration of a variety of neuropsychological instruments, and observation and assessment on PD patients in a clinical setting.